The present invention relates to anhydrous antiperspirant stick compositions. More particularly, the invention is directed to esthetic and efficacious antiperspirant compositions based on anhydrous basic aluminum systems in stick form for application to the human axilla.
It has been known in the art for many years to prepare various cosmetic compositions, including deodorants and antiperspirants, in stick form, such as the well-known cologne sticks or soap sticks. Such cologne sticks or soap sticks were very popular due to their high degree of cosmetic elegance. Unfortunately, these hard, gel-like formulations were unsuitable for use in making stick form antiperspirant compositions.
Thus, the cologne stick or soap stick formulations were based upon sodium stearate-ethanol-water emulsions. Such soap base emulsions are incompatible with the usual active antiperspirant ingredients, particularly the acidic, astringent aluminum salts. As a consequence, attempts have been made for many years to achieve the elegance of the cologne stick via other avenues in order to accommodate the aluminum salts. However, such attempts have never been completely successful for a number of reasons, including decreased efficacy of the aluminum salts and failure to duplicate the high degree of cosmetic elegance of the cologne sticks.
One such early attempt at solving these problems is U.S. Pat. No. 2,890,987 issued to Hilfer on June 16, 1959 and assigned to Witco Chemical Company. According to this patent, the sodium stearate or soap base system was replaced by the combination of a solid fatty acid amide of an alkylolamine and an alkylene polyhydric alcohol. While such systems were apparently compatible with the active aluminum salts, they lacked a high degree of cosmetic elegance. Thus, such stick formulations had a very wet feel and slow drying characteristics due to the presence of about 10 to 25 weight percent of water in the formulations.
Other notable attempts at solving these problems are represented in U.S. Pat. Nos. 2,732,327; 2,933,433; 2,970,083; 3,255,082; 3,259,545 and 3,553,316. These patents illustrate attempts to solve the problems by means of either providing a stabilizing ingredient for the sodium stearate or soap base or complexing of the aluminum salt in order to render it compatible with various soap bases. However, in many of these cases the achievement of compatibility was compromised by reductions in the efficacy of the aluminum antiperspirant compounds. Moreover, in each of these cases, superior cosmetic elegance was not achieved due primarily to a wet feel and slow drying characteristics from the high percentages of water present in the formulations.
More recently, at least one proprietary antiperspirant formulation has been developed based upon the system disclosed in the Hilfer U.S. Pat. No. 2,890,987. Such formulation includes about 30 weight percent Emcol 70 (a stearic acid monoethanolamide), about 28 percent propylene glycol, about 15 percent Emcol 249-3K (a propoxylated alcohol emollient), about 20 weight percent Rehydrol (a propylene glycol complex of basic aluminum chloride according to U.S. Pat. No. 3,420,932) and about 7 percent water. Although such composition produces a quite satisfactory antiperspirant stick in many respects, it is still rather slow drying, hard and lacking in good slip-feel and other esthetic characteristics.